Guillermo del Toro is making the biggest splash of his life with Best Picture winner at the Academy Awards The Shape of Water. A spin on Beauty and the Beast that could only have sprung from the imagination of the man who made Spanish Civil War fantasy Pan’s Labyrinth, the film has been winning awards since taking the top prize at the Venice Film Festival last year.

The movie won Best Picture, and had 13 nominations at the Oscars. The bizarre love story between a mute cleaning lady (Sally Hawkins) and an Amazonian fish-man (Doug Jones) is one of Del Toro’s proudest achievements to date. He has put his next project on hold, to bang the drum for the film around the world.

“I made the big mistake of finishing Devil’s Backbone [a moving ghost story set in a Spanish orphanage] and going immediately into [vampire action-horror movie] Blade II,” he explains.

“I have the nagging notion that I should have promoted The Devil’s Backbone more, because it’s still one of my favourite movies and it’s still a movie that not many people know. And I don’t want it to happen again.”

Del Toro puts his heart and soul, not to mention often his own money, into his films, and The Shape of Water was no exception. But while The Devil’s Backbone, for example, was, he says, “easy” to make, The Shape of Water was “horrible” and “brutal”, he admits.

“Every day I got out of bed and felt like I was going to curl up in a ball and die,” he recalls, grimacing. He sunk his entire salary – “and more” – into the project, but trying to make “a US$60 million [Dh220m] movie for $19m, which is insane” was always going to be tough.

“Firstly, I wanted to shoot it with the camera always moving, and that’s not fast. It takes a long, long time, and I didn’t have it,” Del Toro says. “On top of that, it took three years to make the creature – and we were tweaking it until the last moment – and then every meteorological thing that could go against us, went against us: cold, rain, sandstorms, whatever you want.” He laughs. “Some things I cannot discuss because of insurance, but a lot of it went wrong.”

Nevertheless, the film he had in his mind when he co-wrote the screenplay ended up more or less intact. “So there is a healing effect and it becomes a dear movie,” he says. “It doesn’t have to be that anyone else agrees. People may say: ‘Well I like this other one much better’. To which I go: ‘God bless. That’s fine.’”

When Del Toro first conceived the idea for the film in 2011, then started writing it in 2012, the Trump era and its divisive racial rhetoric was still unimaginable to most. As a Mexican who moved to the United States for safety following the kidnapping of his father (Titanic director James Cameron paid his abductors’ $1m ransom demand), however, Del Toro says he is very sensitive on a personal level to the way foreigners are treated, and “I thought: ‘This is coming. Somehow, this is coming.’”

He set The Shape of Water in America in 1962, but he is really talking about today and what it feels like to be an outsider or part of a minority, who in story terms is represented by characters such as Hawkins’ silent Elisa and her fish-out-of-water lover; an artist and a black co-worker. On the surface, the US of the film oozes confidence and optimism. It is the US, says Del Toro, that people have in mind when you hear “Make America Great Again”. It is, though, rotting from within.

“They’re actually talking about an America which never existed,” he says. “In 1962, everything was idealised about the future, but it was a future that never really came to be. The cars had jet fins, the kitchens are beautiful, everything is automatic, everything is modern, but in ‘63 Kennedy is shot and that Camelot collapses. It never really happens. So it’s not a movie about ‘62. It’s a movie that tells you that the racism, classism, sexual mores, everything that was alive in ‘62, is all alive now. It never went away.”

Del Toro has always considered himself an outsider. As a filmmaker, he has never felt like he belongs anywhere. “I’m too full of genre for the art film and I’m too full of art for the commercial film. I’m weird,” he laughs. As an immigrant, he is often made to feel different. “I may have light skin and sort of lighter hair, but the moment I open my mouth in immigration, all that goes away. When I’m stopped many times by a cop on a traffic violation and I speak, I am immediately a Mexican. So these are things I am trying to say [in the film].”

Even as child, in his own strict Orthodox Catholic family, he was the odd one out. “I grew up in a household that told you the right way to act, how to dress, how to behave, how to be brave and how imagination was weak.” He rebelled and let his fantasies run wild by drawing imaginary beasts and writing stories. To his grandmother, he had gone over to the dark side. “I was exorcised by her. Twice,” he recalls. “It’s funny [now], but it was not funny at the time. She really went in with a vial of holy water and tried to exorcise me for the [things] I was drawing. I started laughing and she got so scared that I was laughing at the holy water that she threw more at me.”

Having grown up in a Mexico riven with violence, where “death and cadavers were a part of my daily life”, makes it easy to understand why he wanted to escape into his own world and why monsters have become one of the things he loves most. “As a kid, I knew that monsters were far more gentle and more desirable than the monsters living inside ‘nice people’,” he explains. “And I think accepting that you are a monster gives you the leeway to not behave like one. When you deny being a monster, you behave like one.

“It’s a very simple paradox that you understand when you find that tool to allow yourself to stop hating yourself. There are truths about oneself that are really bad and hard to admit. But when you finally have the courage and say them, you liberate yourself. And monsters are a personification of that.”

It is a story of liberation in which the fish-man helps his human love to become her real self. At a time of division and exclusion, Del Toro wants to bring people together through love. The film is a love letter to the movies and a love letter to love itself, but also a compassionate celebration of the things that bind us together rather than separate us.

“To me, it was important to make it about a thing that is stronger than anything, which is water or love,” he says. “The strongest element is water, because it is malleable. And it has no shape. And love is the same. Love takes the shape it needs to take. No matter what the shape is, you fall in love madly. I do believe it.”

Will the Academy show its love by turning its nominations into gold? The outcome may be influenced by allegations of plagiarism (which emerged during the writing of this story) from the estate of Pulitzer-winning playwright Paul Zindel, which has drawn attention to similarities between the movie and the late writer’s 1969 play Let Me Hear You Whisper. Whether or not this proves damaging will be revealed on Oscars night on March 4.